Gottlob Frege [1848-1925] was convinced that his own Frege cases,
according to which a subject may assent a certain sentence and
dissent from another sentence which is exactly like the previous one
but for the fact that a singular term of that sentence is there replaced
by a co-referential expression, did not undermine the idea (which he
implicitly endorsed) that the sense expressed by a sentence is
identical with its truth-conditions. For the truth-conditions of a
sentence mirror not only the sentence’s informational value -
roughly, what is said of what the sentence is about (in the simplest
case, this amounts to be a possible state of affairs made out of
certain objects and properties) - but also its cognitive value - the way
the subject conceives what the sentence is about. This depends on
the fact that the thought expressed by a sentence, i.e. its
truth-conditions, is made out of the senses of the sentence’s
components, which according to Frege are the modes of presentation
of those components’ referents.

In the Fregean camp, the notion of mode of presentation has been
further conceived in a plurality of ways. A mode of presentation may
indeed be taken as having i) a descriptive nature (as a consequence,
the presented object is the entity (if any) which uniquely satisfies
certain conceptual requisites) ii) as having a semi-descriptive nature -
(in such a case, the mode is empirically object-dependent: the
presented object is the entity (if any) which contextually satisfies
certain conceptual requisites) iii) as conceptually object-dependent
(no mode of presentation without an object that mode presents) iv) as
intimately linked with the object it conceptually depends upon (so that
the thought expressed by means of it is not only object-dependent,
but also object-constituted).

Some thought experiments, attuned with Kripke’s new theory of
reference (according to which the meaning of proper and (most)
common names collapses on their reference), have contributed to
discredit Frege’s afore-mentioned conviction. Putnam (1975) and
Burge (1979) have indeed made up two stories which are intended to
show that there may be two physically identical subjects (two twins;
or one and the same subject located both in an actual and in a
counterfactual situation) who share the same conception of the world
although the morphologically identical sentences they utter (as well as
the beliefs these sentences express) have different truth-conditions,
insofar as they have different informational value, i.e. they are about
different things. A similar result has been obtained by Kaplan (1989)
with respect to sentences containing indexicals, i.e. context-sensitive
expressions.

Once we take the sentences uttered in the Putnam/Burge cases as
precisely expressing the beliefs possessed by the subjects involved in
those cases, the above semantical results have immediate
consequences on the issue of the individuation of intentional states.
An intentional state such as a belief has two components, namely
what makes it that kind of mental state (i.e. a belief rather than a
desire, or a state of fear etc.) and what makes it a representational
state, i.e. a mental state endowed with a certain representational
content. (In the old-fashioned phenomenological terminology, this is
the distinction between the quality and the matter of a mental state.)
Moreover, according to whether we conceive the representational
content either as relational, i.e. as depending for its own identity on
the external reality(s) it is about, or as non-relational, i.e. as being
what it is regardless of whether it is about an external reality, we get
two ways of individuating one and the same intentional state. These
ways made Putnam (1975) originally speak of a broad and a narrow
psychological state.

Taken in their simplest versions, externalism and internalism are the
conceptions according to which, pending on the broad vs. the narrow
identification of an intentional state, the content of such a state can
legitimately be conceived only either as relational or as non-relational
respectively. For externalists, the representational content of an
intentional state depends on a reality lying outside the subject of such
a state. For internalists, no external object or event which lies or
occurs outside a subject’s brain (or at most its body) is relevant for
the individuation of the content of an intentional state.

To be sure, however, different versions of both externalism and
internalism are possible. First of all, as suggested by the difference
between the Putnam- and the Burge-cases, externalism divides itself
into natural and social externalism, depending on whether the
environment which is relevant for the determination of a thought’s
content is taken to be the physical environment that thought’s
subject is related with or the social community that subject is taken to
(really or ideally) belong to. Social externalism has a broader scope
than natural externalism. For unlike the latter, which primarily
concerns natural kinds- and mass-terms (as well as the corresponding
conceptual constituents of the thought expressed by a sentence
having those terms), it theoretically applies to all conceptual/lexical
constituents of a thought vs. of the sentence which expresses it
respectively. Moreover, it makes the normativity issue enter the stage.
For a term’s uses which conform to/deviate from the communitarian
(authoritative) ones are (judged to be) correct/incorrect expressions
of the communitarianly determined concept denoted by that term.

On its turn, natural externalism might be taken both in a strong and in
a weak version. There are two readings of the strong/weak dichotomy.
According to the former (cf. McGinn (1989)), strong externalism holds
that an intentional state depends on factors lying in the subject’s
external environment, whereas weak externalism says that a state
only depends on the existence of the external objects it is about.
According to latter (cf. Macdonald (1990), Recanati (1993)), the
strong/weak dichotomy is tied to a type-token one: unlike strong
externalism, weak externalism predicates object-dependence for an
intentional state only qua type, not qua token. As a consequence, the
two versions give different answers, a negative and a positive one
respectively, as to whether it is possible to have a non-object
dependent token of an intentional state.

The weak version of externalism is more flexible than the strong one.
For it allows an intentional state to be about an external object which
is out of its subject’s perceptual scope (as in the case of
misperceptions as well as in the one of local hallucinations). However,
it does not permit a state to be about an object which does not utterly
exist (as in the case of a total hallucination). In such a case, weak
externalism forces the subject of a certain state to redescribe its
content; for that state is not an object-dependent thought, although it
so seemed to its subject. This undermines the alleged first-person
authority on a state’s content, the immediate and privileged
knowledge a subject is supposed to have of the content of the state
(s)he entertains in his/her mind. This is an even bigger problem for
strong externalism, which may ascribe an individual a thought
including in its content an object with which that individual is,
unbeknownst to him/her, causally related.

Internalism has no such problems. For it grows out of the Cartesian
intuition according to which for a state’s phenomenological
appearance it makes no difference whether it is a veridical (i.e.,
something corresponds to it in the outside reality) or a non-veridical
state. This intuition is read by internalists as supporting the idea that
a state has a certain content, transparent to its subject, no matter
whether that state is veridical or not. Take this idea as representing
solipsistic internalism. This position may be articulated in different
forms, according to the different ways an internalist neutralizes the
possibility of a relational, object-dependent, content. As to this
content, i.e. the state’s informational truth-conditions, an internalist
may say either i) that it may receive a syntactic (hence, non-relational)
counterpart (cf. Chomsky (1986)) or ii) that it is superfluous in order
to account for an individual’s conceptual structure (cf. Fauconnier
(1985), Jackendoff (1989)) or even that iii) it may be methodologically
bracketed out insofar as it has no role in psychological explanation
(cf. Fodor (1980)). Typically, the nature of an internalistically
conceived content is taken to be either as the conceptual role or the
non-semantic form of the mental representation the state’s
possessor is in relation with insofar as (s)he has the state of which it
is the content. The conceptual role of a mental representation is taken
to be its causal role in an individual’s mental life, perceptual inputs
and behavioral outputs of that representation generally included (cf.
Harman (1982)). The non-semantic form of that representation is
instead identical with, or at least supervenes on, its physical shape
placed in an individual’s brain. In the supervenience case, that form
will coincide with the syntactico-computational structure of the
representation (cf. Fodor (1980)).

But how can a conceptual role or a physico/syntactic form be a
content? The representational feature, which intrinsically
characterizes the notion of a content, appears here to be lost (cf.
McDowell (1986)). Moreover, if in order to account for the Cartesian
intuition in its more extreme form (the hyperbolic doubt), one
expunges from a content all its relational elements, how can this be
individuated as a content? To account for the latter problem, a less
radical form of internalism - non-solipsistic internalism - is available,
according to which content internally conceived amounts to a mental
file where beliefs externally determined are stored (cf. Recanati
(1993)). I can thus think about an x which does not exist insofar as I
have a “x”-mental file where “x”-beliefs are kept, and these are
externally determined. To appeal to mental files in order to save an
internalistically-based notion of content, however, entails having a
holistical conception of such a content: content is determined by the
whole set of an individual’s beliefs. Content holistically conceived
suffers however from a lot of problems, such as public unshareability,
unlearnability, non-compositionality (cf. Lepore-Loewer (1987),
Fodor-Lepore (1992)).

The problems which respectively affect internalism and externalism
leave further theoretical options open. The first option may be called
world-oriented internalism (traces of it may be found e.g. in
Jackendoff (1989), Lakoff (1986), Marconi (1997)). According to this
option, beyond an internal content intentional states (or the sentences
expressing them) have truth-conditions, but these are not to be
conceived as a certain semantics induced by the Putnam cases would
like to understand them, i.e. as possible state of affairs subsisting
utterly independently from human minds. Rather, they amount to
constructed slices of reality, i.e. of reality as humans take it to be.

A second, and more popular, option is dualism, according to which all
Frege-, Putnam/Burge-, and Kaplan-cases prompt one to bifurcate the
content of an intentional state into a narrow and a broad content (cf.
Block (1986), McGinn (1982); Loar (1988), who adheres to a
social-externalist conception of broad content, speaks of
psychological and social content). Narrow content is content as
internalists take it to be; typically, it is conceived as conceptual role.
Broad content is instead given by the state’s truth-conditions, taken
as a metaphysically independent possible state of affairs.

A main drawback of this position is that it is conceivable that one and
the same intentional state has two completely irrelated contents. To
mend this drawback, Fodor (1987) proposed a contextualist variant of
dualism - inspired by Kaplan’s 1989) notion of character as a
function from contexts to contents - according to which narrow
content is what the state’s broad content is given a context. So
conceived, narrow content may contain relational elements, i.e. those
which enable an intentional state, when entertained in a certain
context, to pick up a particular broad content. Nevertheless, identified
in terms of its narrow content an intentional state may still supervene
on its physical basis; for to identify a state in such a way is to
individuate it in terms of its causal powers, which ultimately depend
on its physical structure (non-relationally conceived).

Different problems with this ‘mapping function’-notion of narrow
content (such as its apparent inexpressibility and its schematic
nature) may have ultimately led Fodor (1994) to reject it. Intentional
states only have broad content, conceived in purely informational
terms: the content of an intentional state is what appropriately
covaries with it (the theory of the asymmetric dependence between
causal laws first advanced by Fodor (1987) is charged to explain what
“appropriately” here means). Insofar as states are so identified, they do not
supervene on, but reliably covary with, their physical non-relational
structure. What prompted one to put forward a notion of narrow
content - all the cases recalled two paragraphs above - may be
explained away in a way or other, so that there are no relevant narrow
content-based generalizations which a scientifically oriented
psychology may be charged to miss.

By so doing, however, Fodor throws out the baby with the bath-water.
For in his rejection of narrow content he implicitly makes the
‘mapping function’- and the internalistically-based notion of narrow content
collapses. This is not to be taken for granted; for the needs that
prompt one to defend the former - basically, to account for the
Putnam-Burge cases - are not the same as those that prompt one to
defend the latter - basically, to account for Frege-cases. Thus, before
dispensing with either notion, one has to acknowledge that these
notions are distinct.

A different possibility is to altogether avoid the narrow-broad content
distinction and make again use a unitary notion of content, suitably
attuned to deal with the different potential counterexamples to it
represented by Frege-cases on the one hand and Putnam-Burge
cases on the other. This is made in Bilgrami (1992) soi-disant
externalist conception of content. To be sure, Bilgrami’s notion of
content is externalist, insofar as in order for a concept constituting an
intentional state’s content to subsist, the beliefs which characterize
such a content must be somehow determined by the causal
interaction of their subject with an external world. However, such a
notion also fits internalist requirements, precisely because such a
content consists in a mental file where indefinitely many beliefs,
somehow relationally determined, are listed. Frege-cases are thus
solved by making different co-referential terms expressing different
concepts holistically characterized by a different list of such beliefs.
Putnam-cases are instead solved by selecting in the beliefs’ list
which constitutes a given concept a subset of beliefs shared by the
Putnamian twins and pretending that this subset characterizes a local
content responsible for twins’ commonality of behavior.

This is not the only way to recover unitariety of content, however.
Another possibility is given by reflecting that to be forced to choose
between an internalist and an externalist conception of content
presupposes to endorse a inner/outer dichotomy regarding the
relationship between mind on the one hand and objecthood on the
other. In other terms, it presupposes to take the question, how can
something inner - the mind - pick up via the representational content
of an intentional state of its something outer - an object, as a genuine
problem. There are however several ways to trivialize this problem,
based on making the object a genuine constituent of an intentional
state. This may be achieved by taking the state as being dependent
on, if not constituted by, the entities it is about, where these may be
further conceived either in realist terms (cf. McDowell (1986)) or as
intensional entities (cf. Castañeda (1989)) or anyway as (directly or
indirectly) mentally constituted items (objects of thought, or of human
discourse).